As far as I can tell, these games were simply developed for larger screens. It's not really a failure, but a developer's choice, and developers can have multiple reasons for the choices they make.
Now what kind of device are you using? A laptop? A desktop PC? If you know how to deal with display settings you may try a higher resolution. 

Assuming desktop, you can enter this into the console

console.log(window.innerWidth);
console.log(window.innerHeight);

It will tell you the virtual size in pixel, that the browser has. This is influenced by Windows settings and browser settings. So a pretty standard 1920x1080 display might actually only offer like 1000x500 pixels. So to the game, it seems you do have a small display.

In my opinion, if the game is "too large", it was not properly coded for fullscreen. That's why some games have trouble with this and others do not.

It is similar for websites. Itch itself is not good at that. The site changes with available width and there are thresholds where certain elements disappear, so you would never now they are there. For example, there is a feedback button on the left side in your settings page. It is visible with 1100 width, but disappears with 1000 width.